Three-times world 3,000 metres steeplechase champion Moses Kiptanui says doping is taking place in Kenyan running camps.
Kiptanui, who won three world titles between 1991 and 1995, is the first high profile former Kenyan athlete to allege the African nation's runners are using performance-enhancing drugs.
He says the fluctuating performances of some Kenyan athletes was enough to arouse suspicion.
Kiptanui says catching drugs cheats is difficult because they doped for specific races and the drugs could not be traced the following day.
Allegations that Kenyan athletes were using drugs surfaced ahead of the Olympic Games last year when German television broadcaster ARD reported systematic doping by Kenya's elite athletes who train in running camps in the Rift Valley region.
Athletics Kenya rejected the accusation and angrily accused the broadcaster of attempting to distract its athletes ahead of the London Games where Kenya performed dismally.